Re: Handling of Interval CAN messages

Joshua,

I have a new jetta GLI with a tune and exhaust, not a race car, but not a
typical sedan either.  I have the same type of system that you can sort of
disable, but it's never really fully disabled.  Similar to your situation I
have a specific set of codes I have to put into the vag-com using a laptop
to fully disable the module.  Just now, not 2 minutes ago, I got into a
joyful tailslide that was immediately culled by the car applying the brakes
on its own. This happens even when I have ASR "disabled".  It's just not
legal for them to allow people to fully disable it.  It is a technology
that saves lives - most people do not know how to control and/or recover
from slides, necessitating this technology.

I will look into the manual later and see if I can offer any pointers.

Perhaps since we are way off topic with CAN should we go off the list with
this conversation?  I don't recall what the rules are...


*--*


*Vincent RoyerElectrical Project CoordinatorIntercontinental Truck Body
<http://itb.ca/default.aspx>*

*email: [email protected] <[email protected]>phone: (604) 576-2971*
*mobile: (604) 861-1057*

On Wed, Jan 21, 2015 at 1:15 PM, Joshua B <[email protected]> wrote:

> Vincent,
>
> I've located and uploaded the service manual. This is already a big
> help... The unit controlling what I need appears to be the "Skid Control
> ECU". The funny thing they do with this unit is even though you actually
> disable the trac & vsc function via the button, it still doesn't completely
> disable the unit. If you are on the track driving aggressively (it's my
> race car) there are cases where the system will start to kick in and apply
> brakes. Cases are turns where a wheel may lift off the surface or trail
> braking at 100+ mph. The only way to completely disable this giving the
> driver full control is a strange cheat code sequence you complete with the
> brakes within 30 seconds of starting the car:
>
> Pull E-Brake 3 times (old on 3rd pull)
> Press brake pedal 3 times (hold on 3rd press)
> Pull E-Brake 3 times (hold on 3rd pull)
> Press brake pedal 2 times.
>
> The result is the 2 lights on the dash just like you get from holding the
> interior button down for 3 seconds except it has completely disabled the
> skid control instead of mostly.
>
> Service Manual:
> https://www.dropbox.com/s/tun4qtpub1rylgn/2013%20Scion%20FR-S%20Repair%20Manual.pdf?dl=0
>
> On Wed, Jan 21, 2015 at 11:18 AM, Joshua B <[email protected]> wrote:
>
>> Excellent. Thank you very much Vincent!
>>
>> On Wed, Jan 21, 2015 at 10:55 AM, Vincent Royer <[email protected]>
>> wrote:
>>
>>> Sure, start with the service manual for the car.  Get the diagrams for
>>> the suspension and ECU, put them in a dropbox or something and share them,
>>> I'd be happy to take a look.
>>>
>>> *--*
>>>
>>>
>>> *Vincent RoyerElectrical Project CoordinatorIntercontinental Truck Body
>>> <http://itb.ca/default.aspx>*
>>>
>>> *email: [email protected] <[email protected]>phone: (604) 576-2971
>>> <%28604%29%20576-2971>*
>>> *mobile: (604) 861-1057 <%28604%29%20861-1057>*
>>>
>>> On Wed, Jan 21, 2015 at 8:31 AM, Joshua B <[email protected]> wrote:
>>>
>>>> Thanks Vincent. I'll look into the BCM side of things as I'm pretty
>>>> certain from further testing that I can't accomplish this over CAN. Anyone
>>>> have any good sources on where to start with monitoring the ECU?
>>>>
>>>> On Wed, Jan 21, 2015 at 10:24 AM, Vincent Royer <[email protected]>
>>>> wrote:
>>>>
>>>>> I wouldn't give up so easily.
>>>>>
>>>>> On many vehicles the switches are controlled by the BCM (Body Control
>>>>> Module), over an isolated bus specific for the human interfaces. The BCM
>>>>> will have another bus that connects to the ECM, which may be what is
>>>>> controlling the actual suspension components. If that's the case, you won't
>>>>> be able to interact at the CAN level with this information while connected
>>>>> to the BCM side CAN. Perhaps the switches are hard wired into inputs or
>>>>> multiplexed in some other way to the BCM. I would try to snoop on the ECU
>>>>> side can bus and see if you can find the message there.
>>>>>
>>>>> Alternatively, you can disconnect the suspension from the ECM (or
>>>>> whatever control module is driving them) and provide your own controller.
>>>>> I imagine the dampening adjustment is just a PWM or stepper type valve that
>>>>> rotates different sized orifices in the damper body to speed up / slow down
>>>>> the transfer of fluid in the shock. It should be pretty simple to map out
>>>>> what the settings do to those solenoids using a multimeter.  Then, get a
>>>>> used "suspension controller" or whatever it is, gut the internals, and
>>>>> provide your own controller inside the case.  That way it will be
>>>>> plug-and-play with the oem equipment. Make sure your new controller has a
>>>>> CAN interface and you would be able to essentially reprogram what each of
>>>>> the settings of the buttons do, to your heart's content.
>>>>>
>>>>>
>>>>> On Wed, Jan 21, 2015 at 6:50 AM, Joshua B <[email protected]> wrote:
>>>>>
>>>>>> That's a sinking blow... I had big ideas for this in my race car.
>>>>>> Anyone have any knowledge of where I should look next for a function that
>>>>>> isn't available over CAN?
>>>>>>
>>>>>> On Tue, Jan 20, 2015 at 9:11 PM, Vincent Royer <[email protected]>
>>>>>> wrote:
>>>>>>
>>>>>>> That's my bet.
>>>>>>>
>>>>>>> I have done the exact same thing with a highway truck, trying to
>>>>>>> control a function using the J1939 message instead of the switch itself. I
>>>>>>> went through the same procedure, and found very similar behavior. It did
>>>>>>> turn out to be the LED on the switch, and had nothing to do with the
>>>>>>> function itself. As it turns out, the switch function in my case was not
>>>>>>> available over CAN.
>>>>>>>
>>>>>>> *--*
>>>>>>>
>>>>>>>
>>>>>>> *Vincent RoyerElectrical Project CoordinatorIntercontinental Truck
>>>>>>> Body <http://itb.ca/default.aspx>*
>>>>>>>
>>>>>>> *email: [email protected] <[email protected]>phone: (604)
>>>>>>> 576-2971 <%28604%29%20576-2971>*
>>>>>>> *mobile: (604) 861-1057 <%28604%29%20861-1057>*
>>>>>>>
>>>>>>> On Tue, Jan 20, 2015 at 11:42 AM, Joshua B <[email protected]>
>>>>>>> wrote:
>>>>>>>
>>>>>>>> Rufus,
>>>>>>>>
>>>>>>>> Thank you for the reply. I believe I caught everything you were
>>>>>>>> saying and you also gave me a possible reason to my results. It's possible
>>>>>>>> I've just discovered the messages controlling/monitoring that light on the
>>>>>>>> dash instead of the backend function. The button changes the mode for the
>>>>>>>> cars suspension and I guess it didn't occur to me that the messages I found
>>>>>>>> could just be turning the light on/off and not actually performing the
>>>>>>>> backend function.
>>>>>>>>
>>>>>>>> On Tue, Jan 20, 2015 at 1:06 PM, Rufus V. Smith <
>>>>>>>> [email protected]> wrote:
>>>>>>>>
>>>>>>>>>  Hi Josh,
>>>>>>>>>
>>>>>>>>>     Most CAN messaging (in my somewhat limited experience) is
>>>>>>>>> really "state" information, rather than "event" information.   You are
>>>>>>>>> looking to cause a "light on" event.  Unfortunately the way the light works
>>>>>>>>> is by receiving the light switch state, and using that to turn off/on the
>>>>>>>>> light output.  If there is any notion of "event", it is done by the device
>>>>>>>>> receiving the switch state, and noticing it has changed from the prior
>>>>>>>>> "state".
>>>>>>>>>
>>>>>>>>>   The button appears to be alternate action, rather than
>>>>>>>>> momentary.   That is, push it once, it goes on and stays on, push it again
>>>>>>>>> and it goes off and says off.    If it was momentary, it would only be on
>>>>>>>>> WHILE IT WAS BEING PUSHED, and off upon release. The light controller would
>>>>>>>>> keep it's own memory of the light state, and your method may have worked.
>>>>>>>>>
>>>>>>>>> Rufus
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> On 1/20/2015 12:26 PM, Joshua B wrote:
>>>>>>>>>
>>>>>>>>> Hello Everyone,
>>>>>>>>>
>>>>>>>>>  I'm new to the list and also new to CAN. My interest in CAN
>>>>>>>>> started when I decided I wanted to know what all was happening with the
>>>>>>>>> network in my modern car. This led to me finally picking up a Kvaser
>>>>>>>>> interface and monitoring the CAN bus. My first goal was to try track the
>>>>>>>>> CAN ID & message that is sent when a specific interior button is pressed.
>>>>>>>>> Once I found the message, I then wanted to attempt sending the message
>>>>>>>>> myself to see if I could get the same result without physically pressing
>>>>>>>>> the button.
>>>>>>>>>
>>>>>>>>>  The first phase of this was a success, but it wasn't as simple
>>>>>>>>> as I expected... It turns out that when the button if depressed (off) the
>>>>>>>>> network is transmitting a specific message in 2ms intervals. The message is
>>>>>>>>> the same except the last byte loops from 0 to 255 over and over.
>>>>>>>>>
>>>>>>>>>  When the button is pressed (on) the message flips the values of
>>>>>>>>> 2 bytes and then continues the loop of the last byte from 0 to 255 in the
>>>>>>>>> same interval...
>>>>>>>>>
>>>>>>>>>  Button OFF = 0         211         7   0   6 192  15   0   0
>>>>>>>>> 0-255 <--Byte Loops
>>>>>>>>>
>>>>>>>>> Button ON   = 0         211         7   8  14 192  15   0   0
>>>>>>>>> 0-255 <---Byte Loops
>>>>>>>>>
>>>>>>>>>  My initial thought was that I could just send the "ON" message
>>>>>>>>> and hopefully the already steady interval messages would somehow follow
>>>>>>>>> suit. That sadly wasn't the case. When I sent my message, the dash light
>>>>>>>>> indicator for the button simply blinked instead of staying on because the
>>>>>>>>> car was still sending the loop of "OFF" messages. I could script flooding
>>>>>>>>> the "ON" messages, but this wouldn't be the proper fix and I assume the
>>>>>>>>> function of the button wouldn't be stable.
>>>>>>>>>
>>>>>>>>>  So my question is what is the best way to go about dealing with
>>>>>>>>> interval packets like this? Is there a way I can get the network to drop
>>>>>>>>> the packets?
>>>>>>>>>
>>>>>>>>>  --
>>>>>>>>> Thanks, Josh
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> --
>>>>>>>>> Rufus V. Smith
>>>>>>>>> FW Telematics
>>>>>>>>> 303 Norwich-New London Tpke.
>>>>>>>>> Uncasville, CT 06382
>>>>>>>>> [email protected]
>>>>>>>>> (860) 848-6600 x 115
>>>>>>>>>
>>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> --
>>>>>>>> Thanks, Josh
>>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>
>>>>>>
>>>>>> --
>>>>>> Thanks, Josh
>>>>>>
>>>>>
>>>>>
>>>>
>>>>
>>>> --
>>>> Thanks, Josh
>>>>
>>>
>>>
>>
>>
>> --
>> Thanks, Josh
>>
>
>
>
> --
> Thanks, Josh
>